Guided Practice 8.1: exploring merge-sort

1. Write a data definition for SortedList. Hint: You will need an invariant.
2. Write two DIFFERENT function definitions for even-elements and odd-elements. Assume the elements of the list are numbered starting at 1.

   EXAMPLES:
   (odd-elements (list 10 20 30 40)) = (list 10 30)
   (even-elements (list 10 20 30 40)) = (list 20 40)
   (odd-elements (list 10)) = (list 10)
   (even-elements (list 10)) = empty
   

[ANSWER]